Hot working vanadium



United States Patent 2,715,765 HOT WORKING VANADIUM Charles M. Brown, Lev-vision, and Arthur E. Shrubsall,

Niagara Falls, N. Y., assignors to Union Carbide and Carbon Corporation, a corporation of New York No Drawing. Application August 6, 1952, Seriai No. 302,987 Claims. (Ci. 29-424) This invention relates to the hot working of metallic vanadium and vanadium-base alloys and has for its principal object a method of hot Working such material while protecting it from oxidation.

Metallic vanadium readily oxidizes if heated in air to temperatures upwards of 500 C. This property of the metal renders it dificult to hot-work. Rather large quantities of vanadium oxide are formed resulting in losses of vanadium, poor surfaces on the wrought material and the accumulation of oxides on the equipment which must be removed before the equipment can be used for working other metals.

These difiiculties are overcome by the invention which is a method of working metallic vanadium and vanadium-base alloys while the metal is protected by a suitable flux which prevents oxidation of the metal and dissolves what oxides are produced. The flux used in the method of the invention is a mixture of the oxides of sodium, boron and silicon and may contain a relatively small proportion of oxide of titanium. More specifically, a satisfactory range of flux compositions is: 5% to 30% sodium oxide (NazO); 30% to 80% boron oxide (B203); to 40% silica (SiOz) and up to 2.5 titania (TiOz). Specific examples of flux compositions which have been used successfully are tabulated below:

Percent Composition Flux B203 SiOz TiO:

In the method of the invention a molten flux is applied to the metal to be wrought, and the metal is brought to working temperatures while protected by the molten flux coating. The metal is then worked in conventional manner but always is protected by a relatively thin but tenaciously adhering coating of molten flux. The working operation is conducted in the temperature range of 600 C. to 1200 C., and after the desired degree of Working has been accomplished, the wrought metal, still protected by the flux coating, is cooled to room temperature. During cooling the flux solidifies. It is easily removed after solidification, for example by sandblasting.

A convenient way of applying the flux coating to metal to be wrought, assuring complete protection of the metal is to prepare a molten bath of flux. The metal is then immersed in such bath and heated to working, temperature while it is in the bath. When the metal is at the desired temperature, it is removed but a thin, uniform layer of flux adheres to it.

The flux compositions described above have a melting point in the range 600 C. to 1200 C. and remain quite viscous at such temperature permitting a wide range of working temperatures. The molten flux dissolves whatever vanadium oxide is formed and by spreading uniformly over the metal and adhering well to it prevents direct oxidation of the metal by the surrounding atmosphere. It also serves to lubricate the metal during the Working operation, promotes the formation of good surfaces on the wrought metal, and protects the working equipment from accumulation of vanadium oxide.

2,715,765 Patented Aug. 23, 1955 It will be noted that in the method of the invention the metal is protected by flux at all times during heating, working and cooling operations. The method thus makes possible the working of metallic vanadium and vanadiumbase alloys without encountering loss of metal, poor surfaces and damage to equipment caused by the pro duction of vanadium oxides.

What is claimed is:

1. In the hot working of metallic vanadium and vanadium-base alloys the improvement which comprises applying a molten flux coating to the metal to be wrought, such flux comprising a mixture of the oxides of sodium, boron, and silicon and having a melting point in the range of 600 C. to 1200 C., working such metal in the range 600 C. to 1200 C. while it is coated with such flux, cooling the metal so wrought, and removing the flux coating therefrom.

2. in the hot working of metallic vanadium and vanadium-base alloys the improvement which comprises applying a coating of molten flux to the metal to be wrought; such flux containing 5 to 30% oxide of sodium, calculated as NazO; 30% to oxide of boron, calculated as B203; 10% to 40% silica; and up to 2.5% oxide of titanium, calculated as TiOz; hot working such metal while it is coated with such flux; cooling the flux-coated, hot-Worked metal; and removing the flux coating therefrom.

3. In the hot working of vanadium and vanadium-base alloys the improvement which comprises preparing a molten bath of flux consisting of 5% to 30% sodium oxide (NazO); 30% to 80% oxide of boron (B203); 10% to 40% silica; and up to 2.5% oxide of titanium (TiOz); immersing the metal to be Wrought in such bath; heating such metal to working temperature in such bath; removing the metal from the bath and working it in the temperature range 600 C. to 1200 C. while it is protected with a coating of such flux; cooling the wrought metal while still coated with flux whereby said flux coating solidifies on said metal; and then removing said flux coating.

4. In the hot working of vanadium and vanadiumbase alloys the improvement which comprises immersing the metal to be wrought in a molten bath of flux consisting substantially of 30% sodium oxide (NazO); 60% oxide of boron calculated as B203; and 10% silica; heating said metal to working temperature in said bath; removing the metal from the bath and working it in the temperature range 600 C. to 1200 C. While it is protected with a coating of said flux; cooling the wrought metal while still coated with flux, whereby said flux coating solidifies on said metal; and then removing said flux coating.

5. In the hot working of vanadium and vanadium-base alloys the improvement which comprises immersing the metal to be wrought in a molten bath of flux consisting substantially of 5% sodium oxide (NazO); 80% oxide of boron calculated as B203; and 15% silica; heating said metal to working temperature in said bath; removing the metal from the bath and working it in the temperature range 600 C. to 1200 C. while it is protected with a coating of said flux; cooling the wrought metal while still coated with flux, whereby said flux coating solidifies on said metal; and then removing said flux coating.

References Cited in the file of this patent UNITED STATES PATENTS 392,468 Sparger NOV. 6, 1888 2,040,283 Swartz May 12, 1936 2,053,408 Pfanstiehl Sept. 8, 1936 2,172,533 Freeman Sept. 12, 1939 2,400,866 Kronwall May 21, 1946 2,570,748 Bain et al. Oct. 9, 1951 

1. IN THE HOT WORKING OF METALLIC VANADIUM AND VANADIUM-BASE ALLOYS THE IMPROVEMENT WHICH COMPRISES APPLYING A MOLTEN FLUX COATING TO THE METAL TO BE WROUGHT, SUCH FLUX COMPRISING A MIXTURE OF THE OXIDES OF SODIUM, BORON, AND SILICON AND HAVING A MELTING POINT IN THE RANGE OF 600* C. TO 1200* C., WORKING SUCH METAL IN THE RANGE 600* C. TO 1200* C. WHILE IT IS COATED WITH SUCH FLUX, COOLING THE METAL SO WROUGHT, AND REMOVING THE FLUX COATING THEREFROM. 